1. Field of the Invention
The present invention relates to a leather-wound steering wheel for steering a vehicle and particularly to a leather-wound steering wheel which comprises a core of a ring portion gripped for steering, a coating layer disposed around the ring portion core, fitting grooves provided in the coating layer so as to be disposed along the sectional circumference of the ring portion, and leather provided for covering the coating layer and having terminals disposed along the sectional circumference of the ring portion so as to be fitted into the fitting grooves.
The present application is based on Japanese Patent Application No. Hei. 11-220360, which is incorporated herein by reference.
2. Description of the Related Art
Heretofore there is a known leather-wound steering wheel in which leather for covering a coating layer of a ring portion is disposed so that its terminals along the sectional circumference of the ring portion are fitted into fitting grooves provided in the direction of the sectional circumference of the ring portion in the coating layer (see Unexamined Japanese Patent Publication No. Hei. 10-226338).
In such a leather-wound steering wheel, external appearance of the leather was made good without worsening the curvature radius even in the case where the terminals of the leather along the sectinal circumference of the ring portion were fitted into the fitting grooves as long as the neighbor of the fitting grooves was made of a hard material such as hard synthetic resin, or the like.
However, if the fitting grooves were shallow, the terminals of the leather were apt to be separated so that the leather could not be disposed stably though the terminals of the leather were fitted into the fitting grooves. In this case, it might be conceived that the fitting grooves in the coating layer itself were made deeper. There was, however, a limitation in the attempt to make the fitting grooves in the coating layer itself deeper because the bottom portions of the fitting grooves interfered with the ring portion core.
The present invention is achieved to solve the aforementioned problem, and it is an object thereof to provide a leather-wound steering wheel in which fitting grooves for leather terminals in a coating layer can be made deeper.
In order to achieve the above object, according to an aspect of the present invention, there is provided a leather-wound steering wheel which comprises a core of a ring portion to be gripped for steering, a coating layer of synthetic resin disposed around the core of the ring portion, fitting grooves provided in the coating layer so as to be disposed along a sectional circumference of the ring portion, and leather disposed for covering the coating layer and having terminals provided along the sectional circumference of the ring portion so as to be fitted into the fitting grooves, wherein reduced portions each having a sectional outer circumference which is reduced toward a sectional center thereof from general portions of the ring portion core are disposed in regions of arrangement of the fitting grooves in the ring portion core so that the fitting grooves can be made deeper.
In the above leather-wound steering wheel, preferably, the reduced portions have taper portions for reducing the sectional outer circumference gradually from the general portions, and ribs protruding radially outward from the sectional center are formed in a direction of sectional circumference of the taper portions.
In the above leather-wound steering wheel, preferably, the ring portion core has a dented groove along a planar circumference of the ring portion.
In the leather-wound steering wheel according to the present invention, reduced portions are disposed in the regions of the fitting grooves in the ring portion core. Hence, the coating layer on the reduced portions can be made thicker. Hence, even in the case where the fitting grooves provided in the coating layer in the positions are made deeper, the bottom portions of the fitting grooves hardly interfere with the reduced portions of the ring portion core so that the fitting grooves themselves can be made deeper.
Hence, in the steering wheel according to the present invention, the fitting grooves in the coating layer can be made deeper. If the terminals of the leather are fitted into the fitting grooves, the leather terminals are fitted into the fitting grooves so deeply as not to be separated therefrom. Hence, binding strength of the leather terminals to the fitting grooves can be improved and stabilized.
If taper portions for reducing the sectional outer circumference gradually from general portions of the ring portion core are provided in the reduced portions and ribs are formed in the direction of the sectional circumference of the taper portions so as to protrude radially outward from the sectional center, the ribs can suppress molding shrinkage in the direction of the planar circumference of the ring portion in the coating layer for coating the ring portion core. Moreover, the ribs for suppressing molding shrinkage are provided not in the general portions of the ring portion core but in the taper portions. Hence, the height of each of the ribs from the sectional center of the ring portion at an end of the rib can be suppressed compared with the case where ribs each having a height allowed to suppress molding shrinkage are provided in the general portions. Hence, molding sink of the coating layer can be prevented from occurring in the regions of the ribs.
If the ring portion core is provided with a dented groove disposed along the planar circumference of the ring portion, a molding material for the coating layer flows easily into regions opposite to the fitting grooves via the dented groove along the planar circumference of the ring portion in the ring portion core even in the case where the fitting grooves are made so deeper that the bottom portions of the fitting grooves are made to abut on the ring portion core. Hence, the coating layer can be molded without any obstacle even in the case where the fitting grooves are made so deeper and deeper that the bottom portions of the fitting grooves are disposed in the ring portion core.
The above and other objects and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.